Jupiter

Jupiter is back. After months of lurking below the horizon, the big boy of the solar system has returned to the night sky. Despite being a billion miles away, far further than anything else I’ve mentioned in this blog to date, this enormous ball of gas and liquid appears to us to be the second biggest object in the night sky. So big in fact, that it literally couldn’t be any bigger. If Jupiter acquired more material it would, bizarrely, shrink in size.

Theoretical models show that if more mass were added to Jupiter it would absorb it stay the same size and simply become more dense. If more mass still were added, creating a planet perhaps three or four times more massive, gravity would take over compressing  the matter and causing the planet to shrink below it’s current dimensions.

Ultimately if more and more matter were added gravity would become so intense as to create pressures great enough to ignite the gases and form a star. It is for this reason that Jupiter is sometimes referred to as a failed star; a slightly unkind description for our king of the planets. It is really nothing of the kind,  stars are quite different , the smallest brown dwarf  is perhaps 50 times the mass of Jupiter.